It is known that many types of machines use a device, known as cam, comprising a cylindrical skirt which has, on its wall, a track that is designed to be followed by at least one follower roller, which is supported by a guide comprised in a rotating structure which is coaxial to said skirt; in particular, the follower roller is kept in contact with the track by adapted means, such as an actuation cylinder, thus providing a situation known as “forced mating”.
Accordingly, the follower roller assumes a rule of motion that is determined by the shape of the track provided on the skirt, and this determines, in cams provided according to the background art, a univocal situation, in that a cam is capable of guiding the follower rollers that are connected to it according to a single and very precise rule of motion.
Obviously, such follower rollers are each connected to means designed to work in the most disparate situations, which can change even frequently during the use of the machine that comprises such rollers, as occurs for example if such means are required to manage objects that can undergo dimensional variations depending on the requests that the machine is called to meet.
This is the case, for example, of machines known as cappers, which are designed to apply pistol-shaped closures, commonly known as triggers, which are provided with a drawing straw that has a variable length as a function of the dimensions of the containers to be capped.